str1="hello world"
str2='hello world'
str3=("'hello "
      "world'")
print(str1)
print(str2)
print(str3)
print('hel\'lo world')
print('123----{0}---{1}---{2}'
      'format(4,5)')
str1='hello'
print(f'123--{str1}')
for i in range(0,101,2):
    print('======开始下载=======')
    if i==100:
        print("下载完成")
    else:
       # print(f'{i}%','[',"*"*(i//2),".")
       str4 = "*" * (i // 2) + "." * ((100 - i) // 2)
       print(f'{i}%[{str4}]')